Regex - Char Class Question

sth has asked for the wisdom of the Perl Monks concerning the following question:

I think I'm missing something here, I hope someone can't tell me why this fails,

  DB<6> $a = 'Apr-Jun03.zip~';

  DB<7> p $a =~ /^[\w.-~]+$/

  DB<8> p $a =~ /^[~\w.-]+$/
1
  DB<9> p $a                
Apr-Jun03.zip~
  DB<10> p $a =~ /^[\w~.-]+$/
1
  DB<11> p $a =~ /^[\w.~-]+$/
1
[download]

...so if I move the '~' off the end of the character class, the match works. I can't figure out why. Any ideas?

Thanks, sth

Comment on Regex - Char Class Question Download Code

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Re: Regex - Char Class Question by Enlil (Parson) on Dec 10, 2003 at 18:28 UTC
I don't think it is so much the tilde(~)being at the end but the hyphen (-) not being on one of the ends. That is, if the hyphen is not at either end of the character class then it becomes a range for whatever two chars it is in between.This should work the same as all the others for instance: `$a =~ /^[-\w.~]+$/` [download] -enlil	[reply] [d/l]
Re: Re: Regex - Char Class Question by diotalevi (Canon) on Dec 10, 2003 at 18:35 UTC
See perlop. If you're going to put a ] or - character into your character class then it has to be either escaped or be placed at the front after the optional ^,	[reply]
Re: Re: Re: Regex - Char Class Question by sauoq (Abbot) on Dec 10, 2003 at 19:33 UTC
See perlop. Actually, see perlre. If you're going to put a ] or - character into your character class then it has to be either escaped or be placed at the front after the optional ^, Or placed at the end immediately before the closing square bracket. The relevant passage from perlre: `If you want either "-" or "]" itself to be a member of a class, put it at the start of the list (possibly after a "^"), or escape it with a backslash. "-" is also taken literally when it is at the end of the list, just before the closing "]".` [download] -sauoq "My two cents aren't worth a dime.";	[reply] [d/l]
Re: Re: Re: Regex - Char Class Question by sth (Priest) on Dec 10, 2003 at 18:43 UTC
I knew I could escape the '-', I just wanted figure out what I was missing, was driving me nuts. Thanks for the reply!	[reply]
Re: Re: Regex - Char Class Question by sth (Priest) on Dec 10, 2003 at 18:39 UTC
..Thanks Enlil! I knew it was something obvious, just needed someone to point it out to me. :-)	[reply]


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